FIG. 5 shows the structure of a piston-cylinder type high-pressure generation apparatus which is the most typical type as a conventional high-pressure generation apparatus, wherein FIG. 5(a) is a sectional front view thereof, and FIG. 5(b) is a sectional view taken along the line A-A in FIG. 5(a).
This high-pressure generation apparatus is designed to insert a piston 102 into a cylindrical cylinder 101 and apply a load to the piston 102 from either side thereof so as to generate a high pressure in a high-pressure space 103. This high-pressure generation apparatus can be comprised of members made of a hard or stiff material to generate a pressure of up to about 30,000 atms. However, the high-pressure generation apparatus has difficulty in allowing a maximum possible pressure to be increased beyond a mechanical strength of the cylinder 101 and the piston 102, and consequently cannot generate a pressure out of the bounds of the mechanical strength. In order to break through this restriction, a high-pressure generation apparatus as disclosed in the following Non-Patent Publication 1 has been developed. This apparatus is an innovative technology capable of generating a high pressure of up to about 60,000 atms in spite of a compact structure.
[Non-Patent Publication 1] Nakanishi T, Takeshita N and Môri N, A newly developed high-pressure cell by using modified Bridgman anvils for precise measurements in magnetic fields at low temperature, Rev. Sci. Instrum., 73, 1828, (2002)
The high-pressure generation apparatus disclosed in the Non-Patent Publication 1 comprises a pair of approximately circular truncated cone-shaped components disposed in opposed relation to one another, and a pressure-generating component interposed between the opposed components. Differently from the aforementioned piston-cylinder type apparatus designed to use components in an elastic region thereof, the pressure-generating component is designed to be used in a plastic region thereof. Based on these components, this high-pressure generation apparatus has succeeded in drastically expanding an upper limit of possible pressure and enhancing the efficiency of pressure generation to a certain applied load while significantly downsizing the apparatus. Further, each of the opposed components has a top portion formed with a cylindrical-shaped depression having a side surface which extends uprightly or vertically. The formation of the depression makes it possible to drastically increase the volume of a pressure-generating space, and encapsulate a liquid inside the apparatus to allow a pressure to be isotropically generated.
However, a maximum possible pressure of this high-pressure generation apparatus is limited to about 60,000 atms, due to breakage of the components caused by stress concentration.